Intraoperative corneal thickness monitoring during corneal collagen cross-linking with isotonic riboflavin solution with and without dextran.

PURPOSE: The aim of this study was to analyze and compare corneal thickness changes during corneal collagen cross-linking procedures performed with isoosmolar riboflavin solution with 20% dextran and without dextran in corneal ectatic diseases.
METHODS: The patients in this study were analyzed in 2 groups: group 1 receiving riboflavin solution containing 20% dextran and group 2 receiving dextran-free riboflavin solution. Corneal thickness measurements were obtained with ultrasonic pachymetry at 6 different time points: preoperatively and at 0, 15, 30, 45, and 60 minutes after epithelial removal and initiation of ultraviolet A irradiation.
RESULTS: Twenty-seven eyes of 27 patients with progressive keratoconus were included in the study. In group 1 (n = 13), the mean preoperative thinnest pachymetric readings were 469.3 ± 8.5 μm, which decreased to 423.8 ± 8.9 μm after deepithelization and further decreased to 385.9 ± 10.9 μm at 15 minutes. The corneal thickness assumed a steady course at the 30-, 45-, and 60-minute measurements (378.9 ± 9.8 μm, 384.5 ± 10.5 μm, and 396.7 ± 9.4 μm, respectively). The initial change was statistically significant (P < 0.01). In group 2 (n = 14), the corneal thickness decreased from 459.4 ± 3.8 μm to 414.7 ± 2.6 μm with deepithelization, after which it increased steadily with the initiation of the dextran-free riboflavin solution. The final measurement in group 2 was 474.1 ± 9.4 μm; the increase at each time point was statistically significant when compared with the previous measurement (P < 0.01).
CONCLUSIONS: Using isoosmolar riboflavin solution without dextran causes a steady increase in the corneal thickness during the cross-linking procedure, as opposed to riboflavin with dextran. This result might be beneficial in broadening the spectrum of cross-linking indications in patients with thin corneas.